In the printing field, there is a widespread use of flexible production masters these days. These are tautly mounted on the plate cylinder, an extension of the production master being able to occur because of the mounting of the production masters on the plate cylinders. From this, there follows a variable production master length which disadvantageously results in a variable print length. This is the case, for example, for flexographic printing plates, which are designed to be flexible and stretchable in a rubber-like manner, so that unknown printing lengths result because of the mounting of the flexographic printing plate on the plate cylinder.
Furthermore, independently of the height of a printing plate, the mounting length is the same for all printing plates, so that different roll-over lengths are able to come about for the individual printing plates because of the different printing plate heights. The same condition obtains if the processing masters are prepared in an insufficiently accurate manner, or are subjected to fluctuations in the preparation. An examination of this effect is described, for instance, in the article, “Printing Length Adjustment in Corrugated Paper Direct Printing”, in the journal Flexoprint of April 2001.
Furthermore, in the case of the occasional printing carrier, it may happen that there is a change in the size of the printing carrier between individual processing procedures, on account of a moisture input or a drying procedure.
Because of the previously discussed variable printing lengths or sizes of the printing carriers, during the course of a printing procedure it may also happen, disadvantageously, that variable printing lengths result for the individual working masters. One result of this are register-inaccurate printing processes for the individual processing masters, and consequently blotted appearances of the overall prints.
It is known that the variable master lengths described are manually corrected. For this purpose, the actual printing lengths of the individual working masters are individually measured on the printed sheets. From these printing lengths for the individual working masters correction values are determined, and these are entered manually into a printing device. It is a disadvantage that this results in complicated and awkward handling, which delays the processing procedure in an undesired manner because it is time-consuming. For a plurality of plate cylinders, whose printing lengths are corrected manually, a disadvantageously high additional processing expenditure may be created.
In the related art it is moreover known that, using a so-called register control function, one may use so-called register marks of various production masters in order to align various part printings with respect to position. For example, from DE 102 41 609 a method and a device are known for determining and correcting an imperfect register.